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[Display omitted] • An energy band-matched efficient photo-Fenton-like reactor was constructed. • Graphitic carbon ring induced successive built-in electric field for PMS activation. • CoWO 4 /GD-CN universally degraded representative contaminants in different fields. • The reaction mechanism enhanced by gradient graphitic carbon rings was proposed. The heterojunction with matched energy band enables efficient peroxymonosulfate (PMS)-based photo-Fenton-like reaction. Nevertheless, the rapid photogenerated charge separation and transfer has been challenging. Herein, we precisely constructed an efficient heterogeneous photo-Fenton-like reactor with successive built-in electric field by gradient doping of coplanar graphitic carbon rings (C gra) into cobalt tungstate/graphitic carbon nitride (CoWO 4 /GD-CN) heterostructure. The as-prepared CoWO 4 /GD-CN exhibited remarkable enhancement with a tetracycline hydrochloride degradation rate constant (0.776 min−1) higher than that of CoWO 4 /CN (0.507 min−1). Theoretical and experimental results demonstrated that the successive built-in electric field enhanced by gradient-doped coplanar C gra ring accelerated photogenerated electrons transfer from the innermost to the outmost layer of CoWO 4 /GD-CN. This transfer drove Co(III)/Co(II) conversion for accelerated PMS activation, leading to enhanced degradation reactivity. CoWO 4 /GD-CN had excellent degradability towards representative contaminants, including carbamazepine (1.0 min−1), 4-chlorophenol (0.920 min−1), sulfamethoxazole (0.90 min−1), bisphenol A (0.933 min−1), atrazine (0.829 min−1), ciprofloxacin (0.589 min−1) and norfloxacin (0.617 min−1) in CoWO 4 /GD-CN/PMS/vis system, respectively. This work provided a novel insight into the gradient-dope modulated photo-Fenton-like reaction and guided the design of efficient photo-Fenton-like reactor. [ABSTRACT FROM AUTHOR]

Limited peroxymonosulfate (PMS, HSO 4 −) activation efficiency resulted from slow metal reduction has been a challenge in visible-light (vis) assisted sulfate radical-based oxidation. Herein, a Z-scheme photocatalyst composed of nitrogen-defect-rich graphitic carbon nitride nanosheets embedded with nickel cobaltate nanoparticles (NiCo 2 O 4 /g-C 3 N 4 -N vac) was elaborately designed to accelerate Ni(III)/Ni(II) and Co(III)/Co(II) cycles for PMS activation in PMS/vis system. The NiCo 2 O 4 /g-C 3 N 4 -N vac exhibited remarkable enhancement with a tetracycline hydrochloride (TCH) degradation rate constant (0.1168 min−1), higher than those of NiCo 2 O 4 /g-C 3 N 4 (0.0724 min−1) and g-C 3 N 4 (0.0233 min−1), respectively. Also, the removal efficiencies of 95.5%, 94.2%, 98.0% and 91.4% for carbamazepine, 4-chlorophenol, atrazine and p-nitrophenol were achieved within 30 min, respectively. Theoretical and experimental results suggested that nitrogen (N) vacancies modulated electric structure to build Z-scheme-charge-transfer platform for rapid reduction of Ni(III) and Co(III), thereby accelerating PMS activation for remarkable removal of emerging pollutants. NiCo 2 O 4 /g-C 3 N 4 -N vac exhibited excellent stability and corresponding electrical energy per order (EE/O) in different water matrix was evaluated. Additionally, TCH degradation behavior, pathways and toxicity of products were analyzed, respectively. This work provided an novel paradigm to design the efficient photo-activator of PMS for environmental remediation. [Display omitted] • Z-scheme NiCo 2 O 4 /g-C 3 N 4 -N vac was designed to accelerate PMS activation. • N vacancies lower barrier for achieving Z-scheme charge transfer route. • NiCo 2 O 4 /g-C 3 N 4 -N vac had remarkable performance for various emerging pollutants. • Lower EE/O values in different water matrix engendered more economic benefits. • Degradation pathway and toxicity of products was proposed. [ABSTRACT FROM AUTHOR]